1. Field of the Invention
The present invention relates to a clamp for a cable duct having, at its open side in a region of free ends of its side walls, inwardly projecting, strip-shaped opening edges with the clamp including an elongate bridge section bridging the open side of the cable duct and having a middle portion, and gripping jaws arranged on each of opposite sides of the middle portion, with at least one of the gripping jaws having a hook-shaped connection portion for engagement with a respective opening edge.
2. Description of the Prior Art
Cable ducts mentioned above are generally used for placing therein electrical cables and conductors. The cable ducts can be mounted in indentations or recesses formed in walls, ceilings, and floors. Often, the cable ducts are arranged on wall surfaces. The most often used cable ducts have a somewhat U-shaped cross-section and have a rear wall from which two side walls projects at a substantially right angle. The side of a cable duct opposite to its rear wall is open and provides for placing of a cable. Also known are so-called corner ducts which are used for being mounted in a corner formed by two butt-joined brick walls. These corner ducts have a triangular cross-section and are formed of a rear wall and two side wall projecting from the rear wall at an obtuse angle or of two side walls connected along their longitudinal sides.
The conventional cable ducts are closed with covers after a cable has been laid-in. The edges of a cover engage in undercuts formed in outer surfaces of the side walls at their free ends. The cable, which is laid in the cable duct, loads the side walls pressing them outwardly. This can cause difficulties during mounting and locking of the cover. In order to provide a better stability of the side wall, which are loaded by the placed-in cable, there are provided different clamps which bridge the opening defined by the free ends of the side wall of the cable duct and are secured on strip-shaped edges which project from the side walls inward and extend in the longitudinal direction of the cable duct.
German Utility model DE-U-79 31 274 discloses a clamp for a cable duct which is secured in elongate slots formed in the strip-shaped edges of the side walls. To this end, the clamp has, at both of its longitudinal ends, two locking fingers which are separated by an elongate slit and are provided with locking hooks which hook from beneath the edges of the elongate slots extending transverse to the longitudinal direction of the slits. The locking fingers can be pressed toward each other by forces acting transverse to the longitudinal direction of the clamp. As a result, the width of the clamp, in the region of the locking hooks, is reduced, and the locking fingers can be withdrawn from the respective longitudinal slots. A locking member, which is arranged in each slit between two locking fingers and which, when necessary, can be removed, prevent an accidental release of the clamp from the inward extending edges of the side walls.
The known clamp can only be secured in longitudinal slots, which are formed in the side wall edges at a predetermined distance from each other. Mounting the clamp at any arbitrary selected point of the cable duct, i.e., in the region of cable duct butt or cover butt is not possible. The release of a mounted clamp, e.g., for placing in of another cable, is very difficult. In order to press the locking fingers toward each other, first the locking member should be withdrawn from a respective slit. To this end, the use of both hand is necessary and, on many occasions, the use of a special tool, e.g., a screwdriver and the like is necessary for withdrawal of the locking member.
German Utility Model DE-U-295 15365 discloses a clamp having, at its longitudinal ends, somewhat U-shaped locking sections. The strip-shaped edges, which project from the side surfaces of the cable duct at their free ends inward, are provided, at least on their outer surfaces, with elongate flutes. In cooperation with corresponding flutes provided on inner surfaces of respective clamp sections, the flutes, which are provided on the side wall edges, form a flute lock. This clamp has a certain advantage in comparison with the clamp described above. It, if necessary, can be displaced along the cable duct and can be secured at any arbitrary selected location of the cable duct. The mounting of the clamp is relatively easy. However, for the removal of the clamp, e.g., to place another cable in the duct, the use of both hands is necessary for releasing the flute lock.
An object of the present invention is to provide a clamp for a cable duct which can be easily mounted at any arbitrary selected location along the longitudinal extent of the cable duct. Another object of the present invention is to provide a clamp for a cable duct that can be displaced along the cable duct to a desired position and that would prevent the cable from falling out of the duct. A further object of the present invention is to provide a clamp for a cable duct that could not be accidentally released, in particular, with a closed cable duct cover. A still further object of the present invention is to provide a clamp for a cable duct that could be simply released, at least at one of its side, with only one hand, e.g., for placing another cable into the duct. Yet another object of the present invention is to provide a clamp for a cable duct that would impart an adequate stiffness to the cable duct so that the duct dimensions would not change and the cover could be mounted with an adequate clamping force.